The present invention relates generally to wireless interconnection of different circuits within a single housing and, more particularly to the use of radio waves and/or light to transfer signals between a plurality of circuit boards in a telecommunications switch or computer housing. The use of a wireless bus across an office or building is known, but use of a wireless bus within a single equipment housing provides advantages not previously appreciated.
A telecommunications switch typically has a housing containing a structural framework or xe2x80x9cchassisxe2x80x9d and an interconnecting device known as a xe2x80x9cbackplanexe2x80x9d or xe2x80x9cmidplane.xe2x80x9d A backplane engages with other circuits on one side; a midplane engages with other circuits on its two sides. The framework defines a plurality of slots. Each slot is adapted for sliding in of a circuit board or card, and for alignment of the card for engagement with the midplane or backplane, typically at a right angle to the midplane or backplane. For example, the midplane can have mounted on it an electrical connector which has a plurality of metal pins which make electrical contact with corresponding sockets or terminals on the card being inserted. Alternatively, the pins can be on the card and the sockets can be on the midplane. However, a major disadvantage of this structure is that the metal pins are vulnerable to bending during insertion of the card, particularly if the pins and sockets are not perfectly aligned. Often, it is difficult to determine visually, during the card insertion process, whether such alignment is proper. Once a pin is bent, the card cannot be properly engaged with the midplane, necessitating repair or replacement of the card or midplane. which is a labor-intensive process. Furthermore, direct electrical contact, between circuit elements on the midplane and circuit elements on the card, means that damaging electrical surges or transients and electrical noise can readily be transmitted between the midplane and the card or cards.
Accordingly, it is an object of the present invention to provide a wireless bus to transmit signals between a midplane or backplane and a plurality of cards, or directly among a plurality of cards within a single housing, to thereby electrically isolate the cards from each other.
Briefly, this is accomplished by replacing the wired connections with a radio channel or an optical signal channel between each card and the midplane or, if no midplane is used, directly between each pair of cards. Thus, there are no pins to be bent. Any probes or antennas used do not physically contact the other cards or chassis. The cards can be easily inserted into or removed from the chassis. Field upgrades to the telecommunications switch or other swaps or exchanges of cards can be carried out quickly and easily.